Standard hearing aids include behind-the-ear (BTE), mini-BTE, and receiver-in-the-canal (RIC) devices. Such hearing assistance devices typically include sophisticated electronics to ensure the sound quality. Often, the designs of in-ear or behind-the-ear hearing assistance devices are limited by the space available at human ears.
Hearing aids, for example, may include sophisticated electronics for suppressing environmental noise and amplifying the speech signal. Moreover, hearing aids may have different styles such as in-canal and inside the outer ear. The limited physical spaces inside the canals or the outer ear of human subject limit the size of circuits that may be deployed in hearing aids. Furthermore, hearing aids do not have the ability to place the microphone or microphone array any appreciable distance from the ear. In addition, the shapes of outer ears of human subjects vary significantly. Therefore, the shape of the hearing aid device may require custom design and fit in accordance with the shape of the ear of the human subject. All of these factors may significantly increase the purchase cost and replacement cost of in-ear or behind-the-ear hearing assistance devices, such as hearing aids.